I agree Seishin, I've found her quite inspiring myself. There isn't much on her in English. Having said that, most of the Japanese sources I've come across say very little. There is a youtube video of her from Japanese t.v. I'll try to find it and translate it for you when I get the chance.

She raises two profound points in this article, both of them concerning the interpenetration of Buddhist practice and everyday life:

When asked about the teachings of the Tendai sect, Setouchi said: “It tells us that we should set aside our own happiness and pray for the happiness of other people. Please pray for the happiness of refugees being hosted by other countries.”

Setouchi also looked back on the days after World War II when Tendaiji was desolated and deserted. She helped revive the temple.

Referring to postwar Japan, she commented: “It was horrific because money appeared almost the only thing that mattered in life.”

She said that what is really important is what people cannot see.

“We cannot see gods and our ancestors,” she said. “It is difficult to understand people’s minds, but it is the most important thing to do as we live our own lives.”

“We should realize that we are kept alive by things we cannot see,” she added.

I currently have my hands on a 2000 edition of her publication "仏教塾 (Buddhism Primer)." It's an est. 260-page volume on basic Japanese Buddhism with some specifically Tendai-related material as well. If it would be of interest to anyone, I can work on some translation when I find the time.